Data over Cable Service Interface Specification (DOCSIS) is an international standard adopted by many cable operators and vendors to provide internet access over existing HFC (Hybrid Fibre Coaxial) infrastructure. It includes embedded Cable modem (eCM) and embedded Set Top Box (eSTB), developed as per eDOCSIS standard issued by Cablelabs. It is widely used as a consumer box for industry for Video on demand, Interactive gaming, OOB messaging etc.
The digital communication between eCM and eSTB, transfers data via different interfaces as described by embedded DOCSIS (eDOCSIS) specification. Embedded DOCSIS (eDOCSIS) specification describes the interface between an embedded cable modem (eCM) with one or more embedded Service/Application Functional Entities (eSAFEs). The eSAFEs can be of various types such as eSTB, ePS, eMTA, eSTB, eTEA, eRouter etc. To support transmission of out of band (OOB) messages between eCM and eSTB, Cablelabs provide DOCSIS Set Top Gateway (DSG) specification that define an interface and associated protocol to support transmission of OOB messages between set top controller and customer premise equipment (CPE).
US2008/0028432 discloses a method and apparatus of Communication between embedded Cable Modem (eCM) and embedded Set-Top Box (eSTB). It describes communication between eCM and eSTB through a number of unidirectional ports where different ports are used for different types of messages. Packets with a predefined format are transmitted over TCP (Transmission Control Protocol) or UDP (User Datagram Protocol) with the physical transmission being implemented by USB (Universal Serial Bus) or Ethernet or an IP address in an upper layer protocol. However, the implementation of the cited art as described is applicable only to certain number of interfaces described under the DOCSIS standard.